Monostable multivibrator



Jan. 20, 1970 P. M. SIMMONS MONOSTABLE' MULTIVIBRATOR Original FiledFeb. 8, 1965 nm w hamhao INVENTOR. PATRICK M.L.SIMMONS ATTO RN EYSUnited States Patent 3,491,256 MONOSTABLE MULTIVIBRATOR Patrick M. L.Simmons, San Jose, Calif., assignor of onehalf to Genevieve I. Hanscomand one-half to Genevieve I. Hanscom, Robert Magnuson, and Lois J.Duggan, as trustees of the estate of Roy M. Magnuson Originalapplication Feb. 8, 1965, Ser. No. 431,122, now Patent No. 3,327,850,dated June 27, 1967. Divided and this application Nov. 7, 1966, Ser. No.592,539 Int. Cl. H031: 3/284 US. Cl. 307273 2 Claims ABSTRACT OF THEDISCLOSURE A multivibrator adapted to be triggered by a relatively shortpulse to produce a relatively long pulse including a Schmitt triggercircuit provided with a time delay circuit connected to the outputthereof. This device is provided with a feedback circuit including atransistor having the base thereof connected to the variable resistor ofthe time delay circuit and having the emitter thereof connected to theinput circuit of the Schmitt trigger. The variable contact of theresistor is employed to control the length of the pulse supplied to theoutput circuit.

This application is a division of application Ser. No. 431,122 filedFeb. 8, 1965, for Apparatus for Separating Produce.

This invention relates to electronic apparatus in general. Moreparticularly, this invention relates to a monostable multivibrator.

An object of this invention is to provide an improved monostablemultivibrator which is adapted to be triggered by a relatively shortpulse to produce a relatively long pulse.

Another object of this invention is to provide an improved monostablemultivibrator with an adjustable regenerative feedback.

Still another object of this invention is to provide a monostablemultivibrator with a long time constant circuit coupled to aregenerative feedback, said multivibrator being adapted to be triggeredby a short pulse which is, for example, one millisecond time duration toprovide an output pulse which may be adjusted by adjusting the variabletime constant feedback circuit so that the output pulse may vary from,for example, 100 milliseconds to several seconds in time duration.

Other and further objects of this invention will be apparent to thoseskilled in the art to which it relates from the following specification,claims and drawing, in which, briefly, the sole figure illustrates awiring diagram of this monostable multivibrator.

Referring to the drawing in detail, there is illustrated a monostablemultivibrator employing transistors 10, 11 and 12. This circuit isbasically of the Schmitt trigger type with a very long coupling timeconstant and regenerative feedback which alters the bistable Schmitttrigger circuit to a monostable multivibrator. The collectors oftransistors and 11 are connected to the positive supply line 15 throughthe resistors .13 and 14. The collector of transistor 10 is alsoconnected through resistor 16 to the base of transistor 11. The base oftransistor 11 is also connected to the negative line through resistor18. The lines 15 and 25 are connected, respectively, to the positive andnegative terminals of a low voltage direct current power supply. Theemitters of transistors 10 and 11 are connected together and to the topterminal of resistor 17, and the bottom terminal of this resistor isconnected to the negative line 25. The

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collector of transistor 11 is also connected to the top terminal ofcapacitor 19 and to the output terminal 23. The bottom side of capacitor19 is connected to the top of resistor 20 which is provided With avariable contact 21 that is connected to the base of transistor 12.Another resistor 22 is connected between the bottom of resistor 20 andthe negative line 25. The collector of transistor 12 is connected to thepositive supply line 15 and the emitter of this transistor is connectedby the feedback line to the base of transistor 10. The input terminal 24is also connected to the base of transistor 10.

The monostabe vibrator is triggered by supplying a relatively shortpulse to the input terminal 24. This triggering pulse may be on theorder of a millisecond time duration. The output pulse supplied to theoutput terminal 25 may be adjusted in time variation from approximatelymilliseconds to several seconds by adjusting the variable contact 21that is associated with the resistor 20 of the RC circuit. This variablecontact 21 is connected to the base of transistor 12 and the emitter ofthis transistor is connected to the base of transistor 10. Thus,transistor 12 provides capacitive regenerative feedback to the base oftransistor 10.

While I have shown a preferred embodiment of the invention, it will beunderstood that the invention is capable of variation and modificationfrom the form shown so that the scope thereof should be limited only bythe scope of the claims appended hereto.

WhatI claim is:

1. In a monostable multivibrator adapted to be triggered by a relativelyshort pulse to produce a relatively long pulse, the combinationcomprising a Schmitt trigger circuit having an input circuit and anoutput circuit, said Schmitt circuit comprising a pair of transistorsWith means connecting the base of one of the transistors to thecollector of the other of the transistors and means connecting theemitters of the transistors together, a time delay circuit connected tothe output circuit of said Schmitt trigger circuit, said time delaycircuit comprising a capacitor and a resistor connected in series, afeedback circuit including a feedback transistor having the base thereofconnected to said time delay circuit, the emitter of said feedbacktransistor being connected to the input circuit of said Schmitt triggercircuit, said time delay circuit having means controlling the durationof the relatively long pulse supplied on the output of themultivibrator.

2. In a monostable multivibrator adapted to be triggered by a relativelyshort pulse to produce a relatively long pulse, the combination as setforth in claim 1, further characterized in that the resistor of saidtime delay circuit is provided with a variable contact connected to thebase of said feedback transistor.

References Cited UNITED STATES PATENTS 2,827,574 3/1958 Schneider 3072732,992,640 7/1961 Knapp 307273 3,035,188 5/1962 Asseo 307290 X 3,084,2664/1963 Williams 307273 X 3,188,489 6/1965 Dorsey 307273 X 3,214,60210/1965 Heyning et a1. 307-273 X OTHER REFERENCES G. Marosi and N.Vinson: Electronic Design, Aug. 30, 1966, pp. 65, 66.

JOHN S. HEYMAN, Primary Examiner I. D. FREW, Assistant Examiner US. Cl.X.R. 307290, 293, 294

